1. Field of the Invention
The present invention relates to an image display system, which is formed from a combination of a display device which displays a plurality of images, which are different from each other, in a time sharing manner and shutter glasses which a viewer of the images wears, and which show a stereoscopic image to the viewer by opening and closing the right and left shutters of the shutter glasses in synchronization with switching of images by the display device, and in particular to a calibration device which performs calibration of the timing of the opening and closing of the shutters of the shutter glasses with regard to the image switching of the display device, an image display system and shutter glasses.
2. Description of the Related Art
It is possible to show a stereoscopic image which is viewed in 3D by a viewer by displaying an image with parallax to the left and right eyes. As one method of showing a stereoscopic image, there is a method of having a user wear glasses with particular optical characteristics and showing an image with parallax to both eyes. For example, a time-sharing stereoscopic image display system is formed from a combination of a display device which displays a plurality of images, which are different from each other, in a time sharing manner and shutter glasses which a viewer of the images wears. The display device displays a left-eye image and a right-eye image alternatively on a screen with an extremely short cycle, and at the same time, provides images to a left eye and a right eye in synchronization with the cycle of the left-eye image and the right-eye image separately. On the other hand, the shutter glasses which the viewer wears transmit light to a left-eye portion of the shutter glasses and block light to a right-eye portion in a case where the left-eye image is being displayed, and transmit light to the right-eye portion of the shutter glasses and block light to the left-eye portion in a case where the right-eye image is being displayed (for example, Japanese Unexamined Patent Application Publication Nos. 9-138384, 2000-36969, and 2003-45343).
In the time-sharing stereoscopic image display system, when the left-eye image and the right-eye image are displayed in a time sharing manner, there is one technical problem in separating the left-eye image and the right-eye image so that crosstalk is not generated. For example, a stereoscopic image display method is proposed which suppresses flicker due to residual images by setting a simultaneous light-blocking state where the left-eye shutter and the right-eye shutter are simultaneously in a light-blocking state to a portion of each frame period due to a period when the left-eye shutter and the right-eye shutter are both switched to the light-blocking state being set to be an earlier period than a period when the frame period is switched (for example, Japanese Unexamined Patent Application Publication No. 2003-304115).
In the time-sharing image display system, typically, the display device generates a standard pulse in synchronization with the switching of the left-eye image and the right-eye image, and notifies the shutter glasses of the timing of the opening and closing of the shutters based on the standard pulse. Then, in the shutter glasses, the left and right shutters are alternatively operated to open and close based on a notified timing of the opening and closing of the shutters signal. In most cases, communication between the display device and the shutter glasses is one-way communication from the display device to the shutter glasses using infrared communication.
In the display device, a delay time is generated from when an image signal is switched (that is, from when the standard pulse is generated) to when the display on a screen is visually switched. The delay time is a phase difference of the timing of the image switching and the timing of the opening and closing of the shutters of the shutter glasses and is a cause of crosstalk. As one method of resolving the phase difference, calibration of the timing of the opening and closing of the shutters may be performed in the shutter glasses with regard to the standard pulse.